An appropriate estimate of statistical power is critical for the design of intervention studies. Although the inclusion of a pretest covariate in the test of the primary outcome can increase statistical power, samples selected on the basis of pretest performance may demonstrate range restriction on the selection measure and other correlated…

The objective of the present study was to evaluate the extent to which students who took a computer adaptive test of reading comprehension accounting for testlet effects were administered fewer passages and had a more precise estimate of their reading comprehension ability compared to students in the control condition. A randomized controlled…

This article describes the effects of an analysis-of-practice professional development (PD) program on elementary school students' (Grades 4-6) science outcomes. The study design was a cluster-randomized trial with an analysis sample of 77 schools, 144 teachers and 2,823 students. Forty-two schools were randomly assigned to treatment, (88.5 hours)…

The purpose of this set of analyses, conducted on a randomized control trial examining the effects of a fourth-grade fraction intervention, was to assess the initial academic deficit severity hypothesis. With this hypothesis, at-risk students with more severe initial academic deficits are expected to profit less from intervention than do students…

This study evaluates the impacts and costs of the Reading Partners program, which uses community volunteers to provide one-on-one tutoring to struggling readers in under-resourced elementary schools. The evaluation uses an experimental design. Students were randomly assigned within 19 different Reading Partners sites to a program or control…

The present study used a randomized control trial to examine the effects of a widely used multicomponent Tier 2-type intervention, Passport to Literacy, on the reading ability of 221 fourth graders who initially scored at or below the 30th percentile in reading comprehension. Intervention was provided by research staff to groups of 4-7 students…

Given the dearth of high-quality curriculum materials aligned with the new standards (NGSS and CCSS) and low student persistence in STEM fields, we sought to develop and test a STEM curriculum that would improve student knowledge, interest, and emotions. A cluster randomized control trial was conducted to assess the impact of Speedometry, a…

This study investigates, through a cluster randomized trial, the impact of "Math in Focus," a core mathematics program modeled after instructional approaches used in Singapore, on third- through fifth-grade students' achievement in mathematics. The program is currently being used in more than 400 school districts in the United States.…

This article examines the effects of one year of exposure to "Learning to Read in a Healing Classroom" (LRHC) on the reading and math skills of second- to fourth-grade children in the low-income and conflict-affected Democratic Republic of the Congo. LRHC consists of two primary components: teacher resource materials that infuse…

The purpose of the present study was to examine the effects of a program that offered sustained strategic reading instruction on reading abilities of third and fourth graders. The study was conducted among 1,469 children from 40 schools in the Netherlands. Schools were randomly assigned to either the experimental or control group. Multilevel…